1. Field of the Invention
The present invention relates to a thin film forming apparatus, and particularly, to a thin film forming apparatus capable of efficiently forming a thin film on specific portions on multiple substrates.
2. Description of the Related Art
In various apparatuses such as a portable game machine, a smart phone, a cellular phone, and filming equipment like a digital camera or a digital video, a technique for forming a thin film on a surface of a substrate is used.
Then, in the substrate which is provided in such apparatuses, a thin film may be formed on the entire surface of the substrate, but may selectively be formed only on a specific region on the substrate in many cases.
In this way, in order to selectively form a thin film only on a specific region on the substrate, a technique for covering a portion on which a thin film is not to be formed (hereinafter, referred to as a “non-film forming portion”) with a mask is used in the substrate which is held by a substrate holding mechanism disposed inside a thin film forming apparatus. However, in the technique for covering the substrate with a mask in this way, only a limited number of substrates may be held by the substrate holding mechanism since the respective substrates are generally held by the substrate holding mechanism so as not to overlap a portion on which a thin film is to be formed (hereinafter, referred to as a “film forming portion”) on the substrate. Accordingly, there are problems that films may not simultaneously be formed on a plurality of substrates, and hence the film forming efficiency is degraded.
In order to solve the above-described problems, there is proposed a technique for forming a thin film in the state where the substrates overlap each other so as to cover the non-film forming portion by the other substrate instead of forming the non-film forming portion using a mask (JP 1988-266071A).
Further, JP 1995-34222A proposes a technique for disposing a plurality of substrates in an inclined state using first and second pins to form a thin film near ends of the substrates. In this way, in the substrates arranged in an inclined state, since the substrates serve as a mask therebetween, there is no need to provide a mask for the film forming operation. Furthermore, since the substrates are arranged so as to overlap each other, a large number of substrates may simultaneously be processed.
However, in the technique disclosed in JP 1988-266071A, there is a need to attach an attachment preventing plate which covers the non-film forming portion onto the substrate which is finally placed on the substrate holder, which degrades the operation efficiency. Further, in the technique disclosed in JP 1995-34222A, there is a need to lock the substrate to the first and second pins, which causes problems that the operation of installing the substrate is troublesome and the longer operation time is needed.
Accordingly, in the techniques of JP 1988-266071A and JP 1995-34222A, the more operation time is needed for the film forming operation, which increases a problem that cost for the film forming operation.
Further, in the substrate holding mechanism disclosed in JP 1988-266071A and JP 1995-34222A, the end (the end including the side surface) of the substrate is inevitably exposed, and hence it is difficult to precisely set the shape or the size of the film forming portion. Accordingly, there is a problem that the shape or the size of the film forming portion which can be formed on the substrate is limited.